1. Field of the Invention
This invention relates to a flame-retardant and a flame retardant thermoplastic resin composition. In particular, it relates to a flame-retardant and a flame retardant thermoplastic resin composition which are free from such a toxicity problem due to a halogen gas generated during combustion or molding as in the use of a halogen-containing flame-retardant, are small in such influence on the molding processing characteristics and mechanical properties of a resin as in the use of an inorganic flame-retardant and have long term antistatic properties.
2. Description of the Related Art
Thermoplastic resins have been used in large amounts in a wide field such as automobile parts, parts for domestic appliances, parts for business, industrial parts, miscellaneous goods and the like; however, in some uses, it has been required to make the resin materials to be used incombustible or flame retardant from the view-point of the controlling or minimizing of disasters and the protecting of human life and the like when unexpected ignition or combustion is caused.
The most general method for making a thermoplastic resin flame retardant is to incorporate a flame-retardant into the resin, and is the flame-retardant, there have been used an inorganic flame-retardant, a representative of which is magnesium hydroxide and aluminum hydroxide, and a halogen-containing flame-retardant, a representative of which is decabromodiphenyl oxide.
Many other flame-retardants have also been known, and examples thereof are mentioned in., for example, Fine Chemical, Vol. 20, No. 11 (1991), pp. 9-36.
However, when an inorganic flame-retardant is used, this must be incorporated into a thermoplastic resin, which is the objective base polymer, in an at least equal amount in order to obtain the desired level of flame retarding effect, and this fact adversely affects the light weight, mechanical strength and cheapness, which are the characteristics of the resin, and causes such a problem as reduction of flow properties in molding.
The halogen-containing flame-retardant is characterized in that even when it is used in an amount smaller than that of the inorganic flame-retardant the desired level of flame retarding effect is obtained and hence its effect on the mechanical strength of the resin is relatively small; however, there have been pointed out such a problem that when the compounded resin is exposed to strong heat in combustion or molding, harmful and toxic fumes are liberated and such a fear that the molding machine may be corroded.
On the other hand, a rapid development of a non-halogen type flame-retardant by which such a problem is less caused has recently been made and, for example, Japanese Patent Application Kokai No. 61-106,643 discloses a flame-retardant for polyolefin comprising as an effective component a nitrogen-containing condensed phosphoric acid compound consisting of a condensed phosphoric acid compound such as ammonium carbamyl polyphosphate and a triazine compound such as melamine powder.
In Japanese Patent Application Kokoku No. 60-35,947, Japanese Patent Application Kokai No. 59-147,050, Japanese Patent Application Kokai No. 1-193,347 and the like, a system consisting of an ammonium polyphosphate and a 1,3,5-triazine derivative is disclosed as a flame-retardant for thermoplastic resins.
Moreover, Japanese Patent Application Kokai No. 60-36,542 discloses a fire retardant additive composition consisting of an ammonium polyphosphate and a polyhydroxy low molecular weight compound such as pentaerythritol.
Such prior art flame-retardants are considered to be excellent in that flame retardancy in the desired level is obtained by adding them in a relatively small amount and that they are safe; however, they are unsatisfactory in that flame retardancy is unsatisfactory when they are added in a smaller amount and in that when resins are made flame retardant thereby physical properties are deteriorated and molding processing characteristics and surface appearance of molded article obtained therefrom are also deteriorated.